Backlash comparator



Oct. 30, 1956 H. P. FRY

BACKLASH COMPARATOR Filed Sept. 26, 1952 JNVENTOR.

HORACE P. FRY

United States Patent BACKLASH COMPARATOR Horace P. Fry, West Chester, Pa., assignor to American Viscose Corporation, Philadelphia, Pa., a corporation of Delaware Application September 26,.1952,.Serial No. 311,700

3 Claims. (Cl. 33174) This invention relates to the measurement of backlash in a drive system and particularly to an apparatus for ascertaining the amount of slack or play in a system comprising rotary elements connected in series relationship, suchas those used for driving the godets of a spinning machine. The term godet refers to any roller having a periphery adapted to support a strand and conventional ly' used in the spinning of strands of artificial filaments.

In the conventional viscose rayon spinning machine, the freshly spun yarn is forwarded, as it emerges from a. spinning bath, to a collecting device or additional treatment stations by at least one godet and usually a pair of godets. When two godets are provided, the one which handles the yarn last is driven at a peripheral rate greater than the godet which first receives the yarn, so as to continuously stretch the yarn as it advances from one godet to the other.

Slackness in the drive transmission for the godets may result in backlash, a well-known behavior of loose mechanical driving systems wherein, when the torque load is light, the speed of rotation of a driven member may repeatedly accelerate above and then decelerate below the relatively uniform speed of a driving member. This condition, although it always exists to some degree in a godet driving system, may be of such magnitude as to affect the quality of the yarn.

The undesirable effects of backlash are multiplied in the two-godet yarn-forwarding system since the godet that is disposed rearwardly with respect to the movement of the yarn may be decelerated at the instant the forward godet is accelerated. In this situation, the section of the yarn extending between the godets is stretched substantially more than a section extending between the godets atv another instant when the rear godet is accelerated and the forward godet is decelerated. Such behavior of .the godet system is most likely to occur when spinning .fi-ne yarns since the torque load imposed by the yarn on the godets is very light and not sufficient to maintain constant driving contact of elements, such as intermeshing gears, of a driving system thereof.

It is an object of the present invention to provide apparatus for measuring the backlash in driving systems comprising rotary members and particularly in equipment for supporting filamentary material when such equipment comprises rotary members for advancing a strand product thereof. It is another object to provide apparatus for measuring backlash which maybe readily attached to or detached from a yarn godet. Another object is to provide a device in accordance with the foregoing objects in the form of a single unit which may be used independently of the exterior reference aids. Still another 'object is to provide an auxiliary apparatus for calibrating the backlash-measuring device so as to facilitate the carrying out of the other named objects in an accurate manner. Another object is to improve the quality of multiplefilament strand, particularly those manufactured from regenerated cellulose, by providing apparatus formeasuring backlash of spinning machine godets whereby excesdevice may be placed for rapid calibration.

2,768,449 ICC Patented 0a. 30, 1956 sive backlash may be discovered and the drive system for such godets corrected to maintain the backlash. below a predetermined limit. Other objects, features, and ad;- vantages will become apparent from the following description of the invention and the drawing relating there.- toin which Fig. 1 is a front view of a backlash-measuring device constructed in accordance. with the present invention;

Fig. 2. is a rear view of the apparatus shown in Fig. 1;

Fig. 3 is a view showing the device illustrated in Figs. 1' and 2 attached to a godet, the view being taken normal to the godet axis;

Fig. 4 isv a front elevation partially in section of auxiliary apparatus for calibrating the device shown in Figs. 1 to 3; and

Fig. 5 is, a side elevation of the apparatus shown, in Fig. 4.

In brief, the invention resides in a device, hereinafter called a backlash. comparator, having a frame member adapted to be attached to they periphery of a spinning machine godet or other rotor, a gravity-controlled levelindicating mechanism, and a support for the mechanism mounted pivotally on the frame member to enable an indicia-bearing element carried on the mechanism to be adjusted relative to a gravity-controlled medium. Ancillary to the present invention is apparatus onto which the It com.- prises a rotor having peripheral contour features similar to those of the rotors on which the comparator is to be .used, a spindle for supporting the rotor, and a support or a stand for rotatably supporting the spindle, the spindle having attached thereto an arm, and a stop means disposed radially from the spindle axis to limit the rotation of the arm to a predetermined angle.

Figs. 1 to 3 illustrate a backlash measuring device or comparator comprising a base or frame 5, a beam 6 supported pivotably by the frame, a spirit-level gauge 7 mounted on the beam, and a gravitation-level mechanism 8 supported pivotably on the frame 5 by a bracket 9.

The frame 5 comprises a ring portion having a flat radially-extending rearwardly-facing surface 11 for engaging the end surface of a godet or other rotor. Attached to the ring portion are extensions 14, 15, and 16 which project radially from the outer circumference of the ring portion and in an axial direction rearwardly of the surface 11. The extensions 14, 15, and 16 have radially inwardly facing surfaces 18, 19 and 20 which are adapted to overlap the peripheral surface of a rotor, such as the godet 22, in the manner shown in Fig. 3 when the surface 11 of the frame engages the end surface of the godet. The extension 16 has a pin 23 fixed rigidly thereto and extending radially inwardly from its surface 20.

The extensions 14 and 15 support the pins 25 and have passageways 24 which extend radially from the surfaces 18 and 19. Portions of the passageways 24 are occupied as shown by portions of the pins 25. The pins project outside the passageways to resiliently engage the periphery of the godet 22. These pins have enlarged head portions disposed inwardly of the passageway which seat against the shoulder formed therein by the counterbore constructionof the passageways. Springs 26 are held in the larger portions of the passageways by a pin 27 extending through each extension transversely through respective passageways 24. Thus, the pins 25 may move inwardly of their passageways in accordance with the diameter of the rotor periphery over which the extensions 14, 15, and 16 are forced. The periphery of the godet 22 is defined in Fig. 2 by axially extending flutes indicated schematically by the generally circular lines 29, comprising solid zig-zag sections adjacent the extensions14, 15, and 16, and dotted line sections: connecting the zig-zag sections. The radially inner extremities of the ,pins, i. e., the surfaces thereof which engage the periphery of the godet, are preferably rounded or tapered so that the pins may be constructed and angularly disposed with respect to the godet axis to engage to a slight extent the end surface of the godet as they enter respective valleys between the flutes of the godet periphery. However, the arrangement of pins 23 and 25 is admirably suited for engaging a smooth cylindrical peripheral surface of similar diameter of any rotor. The frame 5 is readily adapted for application to a rotor having a concentric radially inwardly-facing surface when constructed with extensions such as 14, 15, and 16 extending from the inner diameter of its ring portion with the direction of the pins 23 and 25 reversed from that shown in Fig. 2.

Extension 16 has a portion 28 projecting from the front face of the frame 5 which is bored to receive a pin 31 on which the beam is pivotably mounted. The beam is thus spaced from the face of the frame to bring the ends thereof directly under the end portions of the handles 33 and 34. The handles have cylindrical shaped surfaces 33:: and 34a, and their end portions are anchored in the ring portion of the frame 5. The end portions of the handles extend as shown in the drawing from opposite ends of the cylindrical surfaces 33a and 34a in a direction generally parallel to the axis of the beam 6. The end portions 33b and 34b serve as detents in an opposing relation with the end portions of the beam 6. The surfaces 33a and 34a provide surfaces adapted to be gripped by the hands of the operator and extend generally parallel with the face of the frame. The portion of the handle 34 enclosed by the surface 34a is hollow and interiorly threaded to receive an adjusting screw 35 having a head 36 and an end portion 37 of reduced diameter which engages the beam 6. The handle 33 is recessed in the end portion thereof adjacent the beam 6 to receive a spring 38 which is compressed between the handle and the beam to urge the beam against the screw 35.

Thus, when the device is placed on a rotor as shown in Fig. 3 with the axis of the rotor being at some alignment varying from horizontal to steeply inclined, the inclination of the beam 6 may be changed by turning the screw 35 until the bubble of the liquid within the transparent tube of the spirit-level gauge 7 is placed in registry with some mark or index on the tube. This adjustment should be made when the rotor with the device mounted thereon has been rotated to one extremity of the range of rotation permitted by the backlash or play in the system for driving the rotor. The rotor and the device are then rotated through the range of play and the new position of the bubble with respect to the indicia of the gauge is noted.

The backlash comparator now being described is provided with another mechanism for obtaining measurements of the backlash which may be compared and checked against those obtained by the spirit-level system just described. The mechanism now to be described is essentially a weightoperated indicator 41 supported by the device in pivotable relationship with a gauge element having a scale 43. The scale 43 moves relative to the point or tip 42 of the indicator when the device is rotated, for example, when the device is placed upon a godet and rotated through the range of backlash. The magnitude of backlash may be measured by the portion of the scale 43 which moves past the point 42 of the indicator while the latter is held to fixed orientation by its weighted portion.

The indicator 41 is rotatably supported on an axle element 44 fixed to the gauge 45. The element 44 has an enlarged portion which extends through a pivotably adjustable support member 46. A set screw 47 extends radially through the bearing portion of the member 46 and may be screwed against the outer surface of the element 44 to secure the gauge 45 in any desired angular position with respect to the member 46. The indicator 41 is mounted for free rotation on a diametrically smaller portion of the axle 44. Means such as a cotter-pin 48 are used to retain the indicator on the axle. The member 46 with the indicator 41 and the gauge 45 attached thereto 4 is supported in a bracket 9 attached by screws 49 to th ring portion of the frame 5. The bracket has a pair of spaced parallel extensions 51 and 52, the latter extension having extending through it in threaded relationship therewith a set screw 53. The extension 51 has a conical boss 55. The set screw and the boss engage recessed end surfaces of the spindle portions 57 and 58 of the member 46. The bracket 9 is attached to the frame 5 to dispose the axis of the indicator 41 and the gauge 45 along the axis of the rotor which supports the comparator when the latter axis is aligned horizontally. When the axis of the rotor is inclined from the horizontal, the set screw 53 may be loosened to allow the indicator and the gauge to seek a vertical orientation. The set screw may be again tightened to improve the stability of the device during use which may involve making a large number of observations on different godets having approximately the same axial inclination. The set screw 47 is loosened whenever. necessary to bring the point 42 of the indicator into registry with a desired reference point of the indicia 43. In using the comparator, it is desirable to compare the results of the weight-operated mechanism with those obtained on the spirit level gauge 7. If desired, observations may be made on the basis of either mechanism used alone. The construction of a comparator may be limited, if desired, to either one of the two gravity-controlled mechanisms described.

For calibrating a spirit-level mechanism of the comparator, a calibrating device 60 is provided, as shown in Figs. 4 and 5, which comprises a stand 61, a bearing 62 fixed to the stand, a rotatable spindle 63 extending through the bearing, a rotor such as the godet 64 shown mounted concentrically on the spindle, an arm 65 fixed to the spindle, and a pair of set screws 67 and 68 in threaded relationship with extensions of the stand 61 for limiting the movement of the arm 65.

To calibrate the spirit level gauge 7, the comparator is placed on the rotor 64 in the relationship shown in Fig. 3 with respect to the godet 22. The set screws 67 and 68 are separated sufficiently to receive a thickness gauge 69 between the end of one of the screws and the arm 65. The thickness of gauge 69 may represent the allowable backlash to be tolerated in the drive system to be examined. With the gauge 69 in place, as shown in Fig. 4, the screw 35 is adjusted to bring the bubble 71 into registry with a mark on the transparent tube of the spirit gauge, for example, line A. The thickness gauge 69 is then withdrawn and the rotor 64 with the comparator placed thereon is rotated to bring the arm 65 in contact with the screw 67. The position of the bubble then shifts to that drawn at B in Fig. 3. Line C may then be scribed on the tube to indicate the position of the bubble at B. Thereafter, in measuring the backlash of godets, the spirit level is adjusted at each godet by turning the screw 35 to bring the bubble adjacent the line A before the range of backlash is measured. If the line C represents the greatest allowable backlash and the bubble shifts to a position beyond that established as hereinbefore described at line C when the comparator and the godet are rotated through the backlash range the drive system for the godet is indicated to need repairing. Coinciding with the establishmentof the zero mark at line A of the spirit gauge, the gauge 41 of the device 8 may be adjusted relative to the indicator point 42 to bring the point 42 into registry with a desired point of the scale 43.

While preferred embodiments of the invention have been shown and described, it is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. A device for measuring backlash between two rotatable members, one of the members having a generally cylindrical surface concentrically disposed about its axis meals of rotation, the device comprising a circular frame having means extending from a circumference thereof in a direction parallel to its axis of rotation adapted to engage said cylindrical surfaces whereby the device is disposed generally over an end of the member, said frame having a concentric radially extending surface for engaging the end of the member, a pair of parallel handles extending parallel to the plane of said radially extending frame surface in spaced relationship with the side of the frame opposite said surface, a beam at least as long as the distance between the handles, means for pivotally supporting the beam on an axis passing transversely to a plane containing the lengthwise axes of the handles, each end of the beam being spaced adjacent the end of each handle, a set-screw extending in a direction parallel to the axis of the handle and in threaded relationship therewith through one of said handles into engagement with the beam, a spring extending in an axial direction being compressibly supported between the handle and the adjacent end of the beam, and a spirit gauge mounted on the beam with its lengthwise direction coinciding with that of the beam.

2. A device for measuring the backlash of a spinning godet within a drive system therefor, the godet having a periphery comprising axially-extending serrations disposed concentrically with respect to the axis of rotation of the godet, the device comprising a circular frame having an axially-facing surface adapted to engage an end surface of the godet, the frame having at least three axially-extending extensions which overlap the godet surface in an axial direction when said frame is placed in generally concentric relation with the godet, each extension being angularly spaced about the axis of the frame from an adjacent extension less than 180 degrees and having a pin extending radially toward the godet periphery, said pin being relatively angularly spaced to enter valleys between the serrations to engage said periphery, said extensions being annularly spaced to trap the peripheries of the godet within the grip of said pins, a pair of parallel handles extending parallel to the plane of said frame surface, the handles being supported in spaced relationship with the side of the frame opposite said frame surface, a beam at least as long as the distance between the handles, means for pivotally supporting the beam on an axis extending transversely to a plane containing the lengthwise axes of the handles, said beam being pivotable to engage an end of either handle, a set screw extending in threaded relation through one of the handles into engagement with the beam, a spring compressibly supported between the other handle and an adjacent opposing surface of the beam, and a spirit-gauge mounted on the beam with its lengthwise direction coinciding with that of the beam.

3. A device for measuring backlash between two rotatable members, one of the members having a generally cylindrical surface concentrically disposed about its axis of rotation, the device comprising a circular frame having means extending from a circumference thereof in a direction parallel to its axis adapted to engage said cylindrical surface whereby the device is disposed generally over an end of the member, the frame having a concentric radially-extending surface for engaging an end surface of the member, said frame comprising a pair of spaced detents extending in a direction generally lengthwise of the axis of the frame, a beam at least as long as the distance between the detents, said beam being pivotally supported by the frame to dispose a surface thereof in opposing spaced relation with surfaces of the detents which face in the same direction, a set screw extending through one of the detent means in threaded relation therewith into engagement with said surface of the beam, a spring extending from the other detent means into engagement with said surface of the beam, and a spirit-gauge mounted on the beam with its lengthwise direction coinciding with that of the beam.

References Cited in the file of this patent UNITED STATES PATENTS 1,377,720 Neif May 10, 1921 1,477,257 Fritz Dec. 11, 1923 2,170,824 Lichtenwalner Aug. 29, 1939 2,285,965 Halstead June 9, 1942 2,325,362 Black July 27, 1943 2,438,229 Price Mar. 23, 1948 2,495,765 Rauscher Jan. 31, 1950 2,541,641 Dodson Feb. 13, 1951 2,581,630 Carrigan Jan. 8, 1952 FOREIGN PATENTS 25,439 Great Britain 1912 60,156 Switzerland May 24, 1912 18,932 Denmark June 23, 1914 827,831 France May 4, 1938 

